1. Field
One embodiment of the invention relates to a plug used to supply power to electronic devices.
2. Description of the Related Art
For example, Jpn. Pat. Appln. KOKAI Publication No. 2002-373729 discloses a plug used for a charger-use cable for an electrically powered wheelchair. The plug includes a rod-like core conductor, a cylindrical outer conductor that surrounds the core conductor, an insulation cylinder provided between the core conductor and outer conductor, and an insulation housing that supports the proximal ends of these members. The core conductor includes a neck portion that has a narrow diameter in the vicinity of the distal end portion and an insulation piece that engages with the neck portion and covers the distal end portion. The insulation cylinder extends outwards such as to cover the distal end portion of the outer conductor.
In the plug, the distal end portion of the core conductor and the distal end portion of the outer conductor are each covered with an insulating material. With this structure, the user is protected from electrical shocks by touching these distal end portions.
However, after repetitious plug-in and plug-out, it is highly possible that the insulation piece that covers the distal end of the core conductor may be deformed in the conventional case. Due to the deformation, the insulation piece may be detached from the neck portion, and thus there is conventionally a drawback of the durability of the plug. Further, when forming the neck portion, it is necessary to provide a separate step of processing the core conductor, and thus the manufacturing process for the plug is complicated. Furthermore, if the insulation piece is made of a resin, not only a forming mold exclusively used for the preparation of the insulation piece is required, but also the number of parts required is increased, which causes an increase in the production cost.